This invention relates generally to power semiconductor diodes and rectifiers, and more particularly the invention relates to a power diode having a reduced on resistance and higher reverse breakdown voltage.
A two-terminal power diode or rectifier must have a low turn-on voltage, fast turn-off voltage, and nonconductance when the diode is reverse biased. In addition, the on-resistance must be low and the reverse bias breakdown voltage must be high. However, the necessary doping for low on-resistance can adversely affect reverse breakdown voltage.
Three-terminal vertical MOSFET devices are known which have an alternating P and N doped channel region for connecting a source region on one surface to a drain region on an opposing surface. The alternating P and N regions provide a balanced space charge and reduced electric field below the critical field strength at which avalanche breakdown would occur. Yet the on resistance is not adversely affected. See for example, U.S. Pat. Nos. 5,216,275; 5,438,215; 6,274,904; 6,274,904, 6,037,631; and 6,066,878, for example.
The present invention is directed to improving the characteristic of two-terminal power diodes, such as Schottky and gate controlled power diodes, by including a vertical superjunction region having alternating P and N doped regions for connecting an anode on one surface with a cathode on an opposing surface.
In accordance with the invention, a two-terminal power rectifier, such as a Schottky or gate controlled diode, is provided with a conductive channel having alternating P and N doped regions between the two terminals. The alternating doped regions enhance the reverse bias breakdown voltage while maintaining a low on resistance between the two terminals. The connective channel can have stripped P and N doped regions or meshed P and N regions.
The invention and objections and features thereof will be more readily apparent from the following detailed description and the appended claims when taken with the drawings.